1. Field of the Invention
This invention relates to an improved high-efficiency electrostatic air filter device. More particularly, the invention relates to an electrostatic air filter device for use in the cleaning of air in a room, which device has a very high efficiency and a long service life.
2. Description of the Prior Art
The so-called HEPA (high-efficiency particulate air filter) is widely used in the prior art. It has a high dust-collecting efficiency, however, the head loss is quite high when dust-laden gas is passed through the filter.
If the pores of the filter are made coarse in order to reduce the head loss, the efficiency of dust collection is lowered. If the head loss is decreased by reducing the velocity of the gas to be treated, the size of the filter must be increased. In addition, there have been other disadvantages in that the head loss is increased with the filling of pores, and that the life of the filter is short. Therefore, a suitable pre-filter is often employed in order to extend the life of such a filter.